Principles of fuel cells
Fuel cells convert chemical energy directly into electrical energy andheat. In this respect, fuel cells are comparable to batteries. Howeverin contrast to batteries or accumulators, the chemical reactants aresupplied continuously. This makes it interesting for durable operationin many applications.
Due to its principle, fuel cells feature numerous advantages, which makethem attractive for new products and sustainable supply structures:

• High electrical efficiency (from full to part load)
• Low noise emissions, as few moving parts (only in peripheral devices) are necessary
• Up to 50% lower ratio of CO2 emissions compared with conventional power stations
• Almost no emissions of pollutants like NOx, SO2, and CO

Fuel Cell Types
A large diversity of fuel cell types exist that differ in the kind of the electrolyte and the operation temperature. So the right cell can be found for every application.
Numerous materials and shapes support the electrochemical process, which is going on in fuel cells. All cells do have one common characteristic: a conductive electrolyte that separates anode and cathode and allows only ions (as charge carriers) to pass. The electrons that are required for the chemical reaction have to move via the external electrical circuit - providing electrical power. The driving force is an oxygen partial pressure difference between cathode air and anode fuel. This mentioned principle underlies all fuel cells known until now.
Fuel cells are distinguished in according to its type of electrolyte material. This can be liquid or solid, it can comprise leach, polymer, salt or ceramic and determines the operating temperature. Relating to the material, temperatures vary form ambient up to 1000 °C that usually define the typical application fields.